This invention is directed to an antenna and, in particular, to an antenna for scanning a passive transponder utilized in a system for identifying animals.
Transponder scanners are known in the art. These transponder scanners utilize an antenna to transmit and receive signals from a passive transponder. One such use is a transponder embedded in an animal. The antenna includes a ferrite bar having a thick gauge cable densely wound about the ferrite bar. The antenna transmits a 400 KHz signal which is received by the transponder embedded in the animal and returns a signal of 40 KHz and 50 KHz. This signal is coded in accordance with a combination of 40 KHz and 50 KHz portions of the transmitted signal to correspond to a preprogrammed ID number stored in the passive transponder's chip. The ID number is preprogrammed at the time of manufacture. This ID number allows identification of the animal in which the transponder is embedded. The scanner then inputs this coded ID number into a microcomputer for processing. The prior art transponder scanners are by necessity also bulky in size having large circular shapes to accommodate the thick wires.
These prior art scanners have been less than completely satisfactory because of background noise interference. The television monitoring screen or computer CRTs used in conjunction with the microprocessors which are used during scanning also operate at a 40 KHz and 50 KHz RF signal. There is very little shielding on such monitors. These monitors have a high power output and, accordingly, they interfere with the operation of the scanner when the scanner is used in the proximity of computers and other various monitors. Additionally, the large size of the prior art scanners prevented the scanning of animals within the animal's habitat in that the scanner was unable to fit within the animal cage. Accordingly, it became necessary to remove each animal in order to be scanned.
Furthermore, ID numbers are used as a shorthand manner for presenting data concerning the animal. However, the system user must use the preprogrammed ID number to identify the test animal. This requires the user to match his animal information to the preassigned transponder ID number resulting in an increase of time and effort.
Therefore, a transponder scanner for scanning passive transponders operating at the 40 KHz and 50 KHz frequency signal range, which may be utilized within the animal habitat and in the proximity of the microcomputers necessary for monitoring such animals and mapping the scanned code into a useable in house code, is provided by the instant invention.